In our city, there are two branches of the YMCA. Each, of course, has a scale. Same type, same model. And I have found a 9 pound discrepancy between the two, even though I checked both of them at the 0-balance.

When I weighed at one branch on Wednesday, I noted a 5-pound loss from the last time I weighed, before I sprained my hip and had to stop working out for a couple of months. Weighing again at the other branch on Friday (out of sheer curiosity) I noted a 4-pound gain from that point!

Here are the questions:

If one of the scales is inaccurate, how do I tell which one?

If both scales are accurate, what would account for a 9-pound gain over two days?

Understand I didn't expect to see any change over 2 days. I was testing to see if the two scales agreed with each other, and I sure got my answer.

Thanks for your insight.

scales like that can be easily damaged making them inaccurate, and at a Y anybody and their mothers can play around with them. I would suggest buying a home scale and going by that. if you don't want a home scale around for whatever reason, pick one of those scales and just use that to measure the changes. the only way (I can think of off the top of my head) to know which one might be right is to weigh yourself on various scales and see what the average number is.

my weight can change considerable from one time of day to another, working out, constipation, TOM, water weight from eating certain foods, yep, all those can change what I see on the scale. even how I stand on the scale can affect it even up to a pound (I have a digital Tanita).

though with the inaccuracies of the scales you're looking at, it doesn't sound to me like you had a 9 lb gain (if I'm understanding you correctly)

Can you take a 20 lb weight (or a couple) from the work out room and weigh it on the scale? That would give you an indication of how close each one is to accurate. Just remember that generally speaking, the higher the weight, the greater the discrepancy. So if you weigh 2 20lb weights and they come in at 41 lbs, when you get on the scale, there might be a greater than 1 lb discrepancy.

I'll probably do that.